1. Field of the Invention
The present invention relates to a magnetic tape apparatus in which a magnetic tape in a cartridge is pulled out and travels and data is read from and written to the travelling magnetic tape by a magnetic head.
2. Description of the Related Art
The magnetic tape apparatus has been widely used as, for example, a backup subsystem for a computer and it has been strongly desired to provide the magnetic tape apparatus in a reduced size to save space. If realized in a small size, the magnetic tape apparatus can be used in a desktop apparatus eliminating the need for maintaining space exclusively for the magnetic tape apparatus. Further, in a magnetic tape apparatus in a library apparatus having a mechanism for automatically exchanging the cartridges, the magnetic tape apparatus which is an engine of a small size helps enhance the efficiency for accommodating the magnetic tapes and contributes to increasing the continuous storage processing capacity.
In the magnetic tape apparatus of this type, the magnetic tape in the cartridge is pulled out by a threader mechanism, anchored to a machine reel, and permitted to travel, so that the data are read out from, or written into, the magnetic tape by a magnetic head. While travelling, the magnetic tape comes into sliding contact with the magnetic head, whereby dust produced from the magnetic tape and the like adheres onto the magnetic head due to the sliding contact. The dust must be removed since it may deteriorate the recording/reproducing characteristics. Therefore, the magnetic head has heretofore been cleaned by bringing a cleaning member such as brush or the like into contact with the magnetic head.
Here, in a state where the magnetic tape is wrapped round the magnetic head, it is not possible to clean the magnetic head, and the cleaning member that is located close to the magnetic head hinders the travelling of the magnetic tape. Therefore, a constitution has been contrived in which, when the magnetic tape is being wrapped round the magnetic head, the cleaning member is brought in a retracted position away from the magnetic head, and when the magnetic tape is no longer wrapped round the magnetic head, the cleaning member moves toward the magnetic head to come in contact with the magnetic head.
More specifically, when the magnetic tape in the cartridge is pulled out by a threader mechanism, a swing arm having the cleaning member attached thereto is pushed by the threader mechanism to move the cleaning member to the retracted position away from the magnetic head, and when the magnetic tape is accommodated in the cartridge, the swing arm having the cleaning member is pushed in the reverse direction to move the cleaning member to a position where it comes in contact with the magnetic head.
In the accompanying drawings, FIG. 12 is a plan view illustrating a cleaning mechanism and a rough arrangement in the vicinity thereof in a conventional magnetic tape apparatus, FIG. 13 is a plan view of a swing arm in FIG. 12, and FIG. 14 is a perspective view illustrating a cartridge.
The magnetic tape is wound in the cartridge, and a leader block 1 is attached to the end of the magnetic tape as shown in FIG. 14. The cartridge is inserted in the magnetic tape apparatus through a cartridge insertion port.
The threader mechanism that is not shown has a threader arm for pulling the magnetic tape out, and a threader pin 2 (see FIG. 12) is provided at the end of the threader arm to engage with the leader block 1. The threader pin 2 moves along a track T indicated by a dot-dash chain line in FIG. 12, to pulls the magnetic tape out and causes it to be anchored to a machine reel that is not shown. This mechanism has been widely known.
FIG. 12 illustrates a state where the magnetic tape is being pulled out, and a swing arm 3 is arranged so as to intersect the track T. The swing arm 3 is rotatably supported by a hinge pin 5 so that the center of rotation is at a position striding over the track T relative to the magnetic head 4 and deviated toward the direction of the track on the side of the cartridge.
In addition, though not diagramed, the swing arm 3 has a mechanism incorporated therein which forcibly causes the swing arm 3 to select, as stable positions, either an approach position at which it intersects the track T and an intermediate portion 3a thereof approaches the magnetic head 4 (position shown in FIG. 12) or a retracted position at which it is pushed back in a direction in which it does not intersect the track T toward the retracted position, in other words, it has a mechanism which expels the swing arm toward either the approached position or the retracted position with the intermediate position therebetween as a boundary.
Referring to FIG. 13, a brush 7 which is a cleaning member is attached to the intermediate portion 3a of the swing arm 3 by using an engaging pin 6. In the state shown in FIG. 12, the brush 7 is in contact with the magnetic head 4. An elongated extension 3b forming an end of the swing arm 3 intersects the track T when the swing arm 3 is at the approach position, and an arch-like extension 3c forming the other end of the swing arm 3 intersects the track T when the swing arm 3 is at the retracted position. A fitting hole 3d for being fitted onto the hinge pin 5 is made in a boundary portion between the arch-like extension 3c and the intermediate portion 3a.
In this magnetic tape apparatus, the magnetic tape is drawn from the cartridge and the threader pin 2 is brought into a position shown in FIG. 12 so as to come into contact with the intermediate portion 3a of the swing arm 3 at the approach position thereby to push it. Therefore, the swing arm 3 turns clockwise. As the threader pin 2 passes on the track T near the magnetic head 4, the swing arm 3 moves to the retracted position whereby the magnetic tape is wrapped round the magnetic head 4 and tape guides 8 and 9.
Then, the threader pin 2 causes the leader block to be anchored onto the machine reel. FIG. 15 illustrates a state where the swing arm 3 has moved to the retracted position. In this state, the brush 7 does not come into slide contact with the magnetic tape; i.e., the magnetic tape is permitted to run so that the data are read out or written by the magnetic head.
To accommodate the magnetic tape in the cartridge after the data have been read out or written, the leader block is separated from the machine reel, and the magnetic tape is wound into the cartridge. At this moment, the threader pin 2 moves together with the leader block toward the cartridge. The magnetic tape that is to be accommodated in the cartridge is rewound in a state shown in FIG. 15. Therefore, the threader pin 2 that has arrived at the position shown in FIG. 15 comes in contact with the arch-like extension 3c of the swing arm 3 at the retracted position and pushes it. Therefore, the swing arm 3 turns counterclockwise.
As the threader pin 2 passes through the track T near the swing arm 3, the swing arm 3 returns back to the approach position shown in FIG. 12, and the brush 7 comes into contact with the magnetic head 4 again. The magnetic tape is accommodated in the cartridge.
Even when the swing arm 3 remains at the retracted position due to some cause at a moment when the magnetic tape is about to be pulled out from the cartridge, the threader pin 2 proceeds to push the arch-like extension 3c back to arrive at the intermediate portion 3a without trouble.
Conversely, even when the swing arm 3 remains at the approach position, for to some reason, at a moment when the magnetic tape is about to be accommodated in the cartridge, the threader pin 2 proceeds to push the elongated extension 3b back to pass on the track near the magnetic head 4 without trouble.
The brush 7 must be moved by more than a predetermined amount irrespective of the size of the magnetic tape apparatus. In the above-mentioned magnetic tape apparatus, the moving amount of the brush 7 is obtained by the turning of the swing arm 3. Here, the swing arm 3 has the elongated extension 3b and the arch-like extension 3c on both sides of the center of rotation and, hence, it is not allowed to move the hinge pin 5 far from the magnetic head 4. In order to move the brush 7 by a required amount, therefore, the swing arm 3 must turn by a greater amount.
In the case of the above-mentioned magnetic tape apparatus, however, the swing arm 3 has a large radius of gyration and, particularly, needs a large distance between the hinge pin 5 which is the center of rotation and the end of the elongated extension 3b. Therefore, an increased space of motion is occupied by the elongated extension 3b. Therefore, the cleaning mechanism, too, occupies an increased space making it difficult to realize the magnetic tape apparatus in a small size.